US5690737AExpiredUtility

Process for forming epitaxial BaF2 on GaAs

62
Assignee: US ARMYPriority: May 19, 1994Filed: May 31, 1995Granted: Nov 25, 1997
Est. expiryMay 19, 2014(expired)· nominal 20-yr term from priority
Inventors:Francisco SantiagoTak Kin ChuMichael F. Stumborg
C30B 29/12C30B 25/02C30B 23/02
62
PatentIndex Score
16
Cited by
4
References
32
Claims

Abstract

A process for growing single crystal epitaxial BaF 2 layers on galliumrsenide substrates by slowly reacting Ba, BaCl 2 , Bal 2 , BaBr 2 , BaF 2 •BaCl 2 , BaF 2 •BaBr 2 , BaF 2 •BaI 2 , BaCl 2 •BaBr 2 , Ba 3 (GaF 6 ) 2 , BAH 2 , or BaO 2 vapor with a clean, hot GaAs substrate at 500° C. to 700° C. in high vacuum until a uniform, thin (˜12 Å) layer of reaction product is formed and then vapor depositing BaF 2 onto the reaction layer at room temperature to 400° C. to form the single crystal, epitaxial BaF 2 layer.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
       1. A process for forming a uniform, single, crystal, epitaxial layer of barium fluoride on a single crystal gallium arsenide substrate comprising: A. vapor depositing barium on a clean, hot single crystal gallium arsenide substrate at a temperature of from 500° C. to 700° C., in a vacuum having a background pressure of 10 -8  millibars or less and wherein the barium deposition is slow enough to allow the barium vapor to react with the gallium arsenide substrate surface and form a uniform, epitaxial coating of barium/gallium arsenide reaction product and continuing until the reaction product layer is completed;   B. heating the barium/gallium arsenide reaction product layer at a temperature of from 500° C. to 700° C. in the absence of barium vapor in a vacuum having a background pressure of 10 -8  millibars or less to remove unreacted barium; and then   C. reducing the temperature of the substrate to a temperature of from room temperature to a temperature less than 700° C. and depositing barium fluoride at a rate of from 1 to 100 Å per minute until the desired thickness of uniform, single crystal, epitaxial barium fluoride has been achieved.   
     
     
       2. The process of claim 1 wherein the temperature in step A is from 550° C. to 650° C. 
     
     
       3. The process of claim 2 wherein the temperature in step A is from 575° C. to 625° C. 
     
     
       4. The process of claim 1 wherein the vacuum in steps A, B, and C has a background pressure of 10 -9  millibars or less. 
     
     
       5. The process of claim 4 wherein the vacuum in steps A, B, and C has a background pressure of 10 -10  millibars or less. 
     
     
       6. The process of claim 1 wherein barium deposition rate in step A is from 1 to 5 Å per minute. 
     
     
       7. The process of claim 6 wherein the barium deposition rate in step A is from 2 to 3 Å per minute. 
     
     
       8. The process of claim 1 wherein the temperature used in step C is from room temperature to 400° C. 
     
     
       9. The process of claim 8 wherein the temperature used in step C is from room temperature to 300° C. 
     
     
       10. The process of claim 9 wherein the temperature used in step C is room temperature. 
     
     
       11. The process of claim 1 wherein the barium fluoride deposition rate in step C is from 1 to 50 Å per minute. 
     
     
       12. The process of claim 11 wherein the barium fluoride deposition rate in step C is from 1 to 5 Å per minute. 
     
     
       13. The process of claim 1 wherein the single crystal gallium arsenide substrate is selected from the group consisting of gallium arsenide single crystal wafers, gallium arsenide epitaxial layers on gallium arsenide single crystal wafers, epitaxial layers of gallium arsenide alloys on single crystal gallium arsenide wafers, heterostructures of super-lattice made of combinations of gallium arsenide alloys on gallium arsenide single wafers, gallium arsenide single crystal epitaxial layers on suitable substrate materials, epitaxial layers of gallium arsenide alloys on suitable substrate materials, and heterostructures of super-lattice made of combinations of gallium arsenide alloys on suitable substrate materials. 
     
     
       14. The process of claim 13 wherein the single crystal gallium arsenide substrate is selected from the group consisting of gallium arsenide single crystal wafers, gallium arsenide epitaxial layers on gallium arsenide single crystal wafers, and gallium arsenide single crystal epitaxial layers on suitable substrate materials. 
     
     
       15. The process of claim 14 wherein the single crystal gallium arsenide substrate is selected from the group consisting of gallium arsenide single crystal wafers. 
     
     
       16. A process for forming a uniform, single, crystal, epitaxial layer of barium fluoride on a single crystal gallium arsenide substrate comprising A. vapor depositing a barium compound that is barium chloride, barium iodide, barium bromide, barium fluochloride, barium fluobromide, barium fluoiodide, barium chlorobromide, barium fluorogallate, barium hydride, or barium peroxide on a clean, hot single crystal gallium arsenide substrate at a temperature of from 500° C. to 700° C., in a vacuum having a background pressure of 10 -8  millibars or less and wherein the barium compound deposition is slow enough to allow the barium compound vapor to react with the gallium arsenide substrate surface and form a uniform, epitaxial coating of barium compound/gallium arsenide reaction product and continuing until the reaction product layer is completed;   B. heating the barium compound/gallium arsenide reaction product layer at a temperature of from 500° C. to 700° C. in the absence of the barium compound vapor in a vacuum having a background pressure of 10 -8  millibars or less to remove unreacted barium compound; and then   C. heating the substrate at temperature of from room temperature to 700° C. and depositing barium fluoride at a rate of from 1 to 100 Åper minute until the desired thickness of uniform, single crystal, epitaxial barium fluoride has been achieved.   
     
     
       17. The process of claim 16 wherein the barium compound used in step A is barium chloride, barium iodide, barium bromide, barium fluochloride, or barium fluobromide. 
     
     
       18. The process of claim 17 wherein the barium compound used in step A is barium chloride, barium iodide, or barium bromide. 
     
     
       19. The process of claim 16 wherein the temperature in step A is from 550° C. to 650° C. 
     
     
       20. The process of claim 19 wherein the temperature in step A is from 575° C. to 625° C. 
     
     
       21. The process of claim 16 wherein the vacuum in steps A, B, and C has a background pressure of 10 -9  millibars less. 
     
     
       22. The process of claim 21 wherein the vacuum in steps A, B, and C has a background pressure of 10 -10  millibars less. 
     
     
       23. The process of claim 16 wherein barium compound deposition rate in step A is from 1 to 5 Å per minute. 
     
     
       24. The process of claim 23 wherein the barium compound deposition rate in step A is from 2 to 3 Å per minute. 
     
     
       25. The process of claim 16 wherein the temperature used in step C is from room temperature to 400° C. 
     
     
       26. The process of claim 25 wherein the temperature used in step C is from room temperature to 300° C. 
     
     
       27. The process of claim 26 wherein the temperature used in step C is room temperature. 
     
     
       28. The process of claim 16 wherein the barium fluoride deposition rate in step C is from 1 to 50 Å per minute. 
     
     
       29. The process of claim 28 wherein the barium fluoride deposition rate in step C is from 1 to 5 Å per minute. 
     
     
       30. The process of claim 16 wherein the single crystal gallium arsenide substrate is selected from the group consisting of gallium arsenide single crystal wafers, gallium arsenide epitaxial layers on gallium arsenide single crystal wafers, epitaxial layers of gallium arsenide alloys on single crystal gallium arsenide wafers, heterostructures of super-lattice made of combinations of gallium arsenide alloys on gallium arsenide single wafers, gallium arsenide single crystal epitaxial layers on suitable substrate materials, epitaxial layers of gallium arsenide alloys on suitable substrate materials, and heterostructures of super-lattice made of combinations of gallium arsenide alloys on suitable substrate materials. 
     
     
       31. The process of claim 30 wherein the single crystal gallium arsenide substrate is selected from the group consisting of gallium arsenide single crystal wafers, gallium arsenide epitaxial layers on gallium arsenide single crystal wafers, and gallium arsenide single crystal epitaxial layers on suitable substrate materials. 
     
     
       32. The process of claim 31 wherein the single crystal gallium arsenide substrate is selected from the group consisting of gallium arsenide single crystal wafers.

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